A microporous vascular prosthesis which has an ideal structural uniformity has been fashioned by students at the State University of Pennsylvania Materials Laboratory under the direction of Eugene White. These prostheses are made from Echinoderm spines and have been fashioned in small tubes with 3 to 4 mm I.D. and wall thicknesses of .5, .75 and 1.0 mm. Three different species with varying pore sizes in the range from 15 to 60 microns have been chosen. These grafts have been implanted in the carotid arteries of dogs and have shown evidence of rapid tissue ingrowth with organization within two weeks. The objectives of the proposal currently underway is to study the short term patency of these grafts and to determine the effect of wall thicknesses and pore size upon the rapidity of tissue ingrowth. A future objective is to study long term patency and to determine the relationship between flow rate and patency to be carried out by restricting the flow in grafts and studying them angiographically over one year. The most satisfactory prosthesis from the short term study will be selected for long term implantation. Criteria for selection of these grafts will be patency and rapidity of "neointima development". The ultimate aim is to apply these tubes as graft in small vessels for coronary artery bypass surgery. BIBLIOGRAPHIC REFERENCE: White, R.A., E.W. White, E.L. Hanson, R.F. Rohner, and W.R. Webb: Preliminary report: Evaluation of tissue ingrowth into experimental Replamineform vascular prostheses. Surgery 79: 229-232, 1976.